Tim Barribeau

The great cultural stereotype of pot smokers is the aging hippy, his or her brain turned to mush by too many years of the demon weed. But it turns out that marijuana really does impair your memory in the short term — and now we understand how that happens.

A new piece of research published in Cell argues that it's not that THC is affecting the neurons directly. Rather, the evidence shows it's hitting the neuronal support system — astrocytes. Also sometimes called astroglia, these cells have generally been regarded as less important than neurons, but their role is now becoming better understood.

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Both astrocytes and neurons have cannabinoid type-1 (CB1R) receptors, and the researchers compared the effects of THC on mice, one group of which were mutants without the receptors on their astrocytes, the other without them on the neurons. What they discovered is that the mice without the astrocyte CB1R receptor didn't have the impairment of spatial working memory, where those lacking the receptor on the neurons did. So it's the astrocytes which cause the memory problems when one takes cannabinoids.

This raises questions about the role that astrocytes play in forming memories, and how the cannabinoids in your body interact with them. And yes, it means we might even be able to engineer a THC using drug that doesn't screw with your memory.
http://dx.doi.org/10.1016/j.cell.2012.01.037